Flow Of Sweat Research Articles

Multilayer patch functionalized microfibrillated cellulosic paper sensor for sweat glucose monitoring.

Electrochemical analysis of glucose monitoring without painful blood collection provides a new noninvasive route for monitoring glucose levels. Thus, in this study, biobased cellulosic papers (methylated and phosphorylated one) based glucose monitoring sensor is developed. To achieve high hydrophilicity, microfibrillated cellulose (MFC) were functionalized using hexokinase mediated phosphorylation (-OH to -[Formula: see text]). The instinctive increased surface charge density from 36.2 ± 3.4 to 118.4 ± 1.2 µmol/g and decrease contact angle (45°-22°) confirms the increased hydrophilicity of paper. Furthermore, functionalized phos-MFC paper increase the capillary flow of sweat, required low quantity (1µl) of sweat for accurate analysis of glucose level. Additionally, chemically induced methyl groups (-CH3) make the sensor more barrier to other chemicals. In addition, a multilayer patch design combined with sensor miniaturization was used to lead to an increase in the efficiency of the sweat collection and sensing processes. Besides, this paper sensor integrated with artificial transdermal drug delivery unit (agarose gel as skin) for monitoring glucose levels in sweat. The patch monitoring system increase the accuracy of sensing with fluctuation in sweat vol. (1-4µl), temperature (20-70 °C), and pH (4.0-7.0). In addition, temperature dependency artificial transdermal delivery (within agarose gel) of drug metformin agrees the measurement accuracy of sensor, called "switch system" without any error. As a result, the reported MFC paper based multi-patch disposable sensing system provides a novel closed-loop solution for the noninvasive sweat-based management of diabetes mellitus.

Microfluidic sweat patch based on capillary force and evaporation pump for real-time continuous sweat analysis.

In addition to the common blood and urine, fresh sweat contains a diverse range of physiological indicators that can effectively reflect changes in the body's state. Wearable sweat sensors are crucial for understanding human physiological health; however, real-time in situ measurement of multiple biomarkers in sweat remains a significant challenge. Here, we propose a wearable microfluidic patch featuring an integrated microfluidic channel and evaporation pump for accelerated and continuous sweat collection, eliminating the need for additional sweat storage cavities that typically impede real-time detection. Capillary forces are harnessed to facilitate the rapid flow of sweat through the detection area, while an evaporation pump based on porous laser-induced graphene enhances sweat evaporation. The synergistic integration of these two components enables an uninterrupted flow of fresh sweat within the patch, ensuring real-time monitoring. The influence of channel size parameters on sweat flow velocity is analyzed, and the optimal width-to-height ratio for achieving the desired flow velocity is determined. By implementing a multi-channel parallel design with chamfering, liquid flow resistance is effectively reduced. Furthermore, the patch integrates sensor modules for sodium ion, chloride ion, glucose, and pH value measurements, ensuring excellent sealing and stability of the assembled system. This work presents a simplified approach to developing wearable sweat sensors that hold the potential for health monitoring and disease diagnosis.

Sweat Sensor Based on Wearable Janus Textiles for Sweat Collection and Microstructured Optical Fiber for Surface-Enhanced Raman Scattering Analysis.

Wearable sweat sensors provide real-time monitoring of biomarkers, enabling individuals to gain real-time insight into their health status. Current sensors primarily rely on electrochemical mechanisms, limiting their capacity for the concurrent detection of multiple analytes. Surface-enhanced Raman scattering spectroscopy offers an alternative approach by providing molecular fingerprint information to facilitate the identification of intricate analytes. In this study, we combine a wearable Janus fabric for efficient sweat collection and a grapefruit optical fiber embedded with Ag nanoparticles as a sensitive SERS probe. The Janus fabric features a superhydrophobic side in contact with the skin and patterned superhydrophilic regions on the opposite surface, facilitating the unidirectional flow of sweat toward these hydrophilic zones. Grapefruit optical fibers feature sharp tips with the ability to penetrate transparent dressings. Its microchannels extract sweat through capillary force, and nanoliter-scale volumes of sweat are sufficient to completely fill them. The Raman signal of sweat components is greatly enhanced by the plasmonic hot spots and accumulates along the fiber length. We demonstrate sensitive detection of sodium lactate and urea in sweat with a detection limit much lower than the physiological concentration levels. Moreover, the platform shows its capability for multicomponent detection and extends to the analysis of real human sweat.

Structure-Function Correlations in the Mechanism of Action of Key Antiperspirant Agents Containing Al(III) and ZAG Salts.

Aluminum hydrolysis chemistry is an important part of modern society because of the dominance of Al(III) as a highly effective antiperspirant active. However, the century-old chemistry centered on aluminum chloride (ACL) is not comprehensive enough to address all of the in vivo events associated with current commercial antiperspirants and their mechanism of action. The present study aims to address the knowledge gap among extensively studied benchmark ACL, its modified version aluminum chlorohydrate (ACH), and a more complex but less explored group of aluminum zirconium chlorohydrate glycine complexes (ZAG salts) toward understanding the mechanism of action under consumer-relevant conditions. ACH, which is the Al source used in the manufacture of ZAG salts, provides a bridge between ACL and ZAG chemistry. High viscosity and gel formation driven by pH and a specific Al(III) salt upon hydrolysis are considered the criteria for building an in vivo occlusive mass to retard or stop the flow of sweat to the skin surface, thus providing an antiperspirant effect. Rheological studies indicated that ACL and aluminum zirconium tetrachlorohydrex glycine (TETRA) were the most efficacious salt actives. Spectroscopic studies, diffraction studies, and elemental analysis suggested that small metal oxide and hydroxide species with coparticipating glycine as well as various polynuclear and oligomeric species are the key to gel formation. At a given pH, the key ingredients (NaCl, urea, bovine serum albumin, and lactic acid) in artificial sweat were found to have little influence on Al(III) salt hydrolysis. The effects of the sweat components were mostly limited to local complex formation and kinetic modification. The in vitro comparative experiments with various Al(III) and ZAG salt systems offer unprecedented insights into the chemistry of different salt types, thus paving the way for engineering more efficacious antiperspirant systems.

Rapid Capture and Extraction of Sweat for Regional Rate and Cytokine Composition Analysis Using a Wearable Soft Microfluidic System

Rapid Capture and Extraction of Sweat for Regional Rate and Cytokine Composition Analysis Using a Wearable Soft Microfluidic System

Numerical modelling of the interaction between eccrine sweat and textile fabric for the development of smart clothing

PurposeLive non-invasive monitoring of biomarkers is of great importance for the medical community. Moreover, some studies suggest that there is a substantial business gap in the development of mass-production commercial sweat-analysing wearables with great revenue potential. The objective of this work is to quantify the concentration of biomarkers that reaches the area of the garment where a sensor is positioned to advance the development of commercial sweat-analysing garments.Design/methodology/approachComputational analysis of the microfluidic transport of biomarkers within eccrine sweat glands provides a powerful way to explore the potential for quantitative measurements of biomarkers that can be related to the health and/or the physical activity parameters of an individual. The numerical modelling of sweat glands and the interaction of sweat with a textile layer remain however rather unexplored. This work presents a simulation of the production of sweat in the eccrine gland, reabsorption from the dermal duct into the surrounding skin and diffusion within an overlying garment.FindingsThe model represents satisfactorily the relationship between the biomarker concentration and the flow rate of sweat. The biomarker distribution across an overlying garment has also been calculated and subsequently compared to the minimum amount detectable by a sensor previously reported in the literature. The model can thus be utilized to check whether or not a given sensor can detect the minimum biomarker concentration threshold accumulated on a particular type of garment.Originality/valueThe present work presents to the best of our knowledge, the earliest numerical models of the sweat gland carried out so far. The model describes the flow of human sweat along the sweat duct and on to an overlying piece of garment. The model considers complex phenomena, such as reabsorption of sweat into the skin layers surrounding the duct, and the structure of the fibres composing the garment. Biomarker concentration maps are obtained to check whether sensors can detect the threshold concentration that triggers an electric signal. This model finds application in the development of smart textiles.

Super-Absorbent Polymer Valves and Colorimetric Chemistries for Time-Sequenced Discrete Sampling and Chloride Analysis of Sweat via Skin-Mounted Soft Microfluidics.

This paper introduces super absorbent polymer valves and colorimetric sensing reagents as enabling components of soft, skin-mounted microfluidic devices designed to capture, store, and chemically analyze sweat released from eccrine glands. The valving technology enables robust means for guiding the flow of sweat from an inlet location into a collection of isolated reservoirs, in a well-defined sequence. Analysis in these reservoirs involves a color responsive indicator of chloride concentration with a formulation tailored to offer stable operation with sensitivity optimized for the relevant physiological range. Evaluations on human subjects with comparisons against ex situ analysis illustrate the practical utility of these advances.

A wearable multisensing patch for continuous sweat monitoring

In sport, exercise and healthcare settings, there is a need for continuous, non-invasive monitoring of biomarkers to assess human performance, health and wellbeing. Here we report the development of a flexible microfluidic platform with fully integrated sensing for on-body testing of human sweat. The system can simultaneously and selectively measure metabolite (e.g. lactate) and electrolytes (e.g. pH, sodium) together with temperature sensing for internal calibration. The construction of the platform is designed such that continuous flow of sweat can pass through an array of flexible microneedle type of sensors (50µm diameter) incorporated in a microfluidic channel. Potentiometric sodium ion sensors were developed using a polyvinyl chloride (PVC) functional membrane deposited on an electrochemically deposited internal layer of Poly(3,4-ethylenedioxythiophene) (PEDOT) polymer. The pH sensing layer is based on a highly sensitive membrane of iridium oxide (IrOx). The amperometric-based lactate sensor consists of doped enzymes deposited on top of a semipermeable copolymer membrane and outer polyurethane layers. Real-time data were collected from human subjects during cycle ergometry and treadmill running. A detailed comparison of sodium, lactate and cortisol from saliva is reported, demonstrating the potential of the multi-sensing platform for tracking these outcomes. In summary, a fully integrated sensor for continuous, simultaneous and selective measurement of sweat metabolites, electrolytes and temperature was achieved using a flexible microfluidic platform. This system can also transmit information wirelessly for ease of collection and storage, with the potential for real-time data analytics.

Detection of Aluminum Chlorohydrate Content in Antiperspirant Deodorants Using Screen‐Printed Silver Electrodes by One Drop Analysis

AbstractAluminum chlorohydrate (Al2(OH)5Cl⋅2H2O, ACH) is an active ingredient in many antiperspirants and deodorants formulation to reduce the body odors (mainly sweat) through interaction with apocrine sweat glands to produce insoluble aluminum hydroxide and free chloride, which then plugs the sweat gland that stops the flow of sweat to the skin's surface. We demonstrated here an one drop (50 μL) electrochemical sensing of the ACH using an in‐built three screen‐printed electrodes assembly containing Ag as working and pseudo reference and carbon as counter electrode system (AgSPE). The free Cl− ion librated from ACH/H2O reaction was detected at AgSPE surface at 0.072 V vs. pseudo Ag reference electrode system in pH 2 phosphate solution by Cyclic voltammetric Technique. Under optimal working condition the AgSPE shows a linear calibration plot in the window of 30–2000 ppm of ACH with sensitivity and regression values of 0.104 μA/ppm and 0.998 respectively. Calculated detection limit is 3.03 ppm. RSD values of intra‐ and interassays were 0.19% and 2.79% respectively. Finally, real sample (antiperspirant deodorant lotions) assays were successfully demonstrated with results comparable to the predicted values.

Erroneous gender differences in axillary skin surface/sweat pH

Assessing accurately the pH of axillary eccrine sweat is of vital importance in the antiperspirant industry. Eccrine sweat pH is a critical parameter in determining the effectiveness of antiperspirants; antiperspirant salts dissolve in sweat and diffuse into the sweat glands, where the resultant acidic solution hydrolyses in more alkaline sweat forming an amorphous metal hydroxide gel, thereby restricting the flow of eccrine sweat. Comparison of the skin surface and sweat pH of males and females reported in the literature shows that, although consistent male/female differences have been observed on the forearm, determination of significant gender-based pH differences across other sites are less conclusive. Studies on the back and infra-mammary regions exhibited significant gender differences in skin surface pH, whereas those on the forehead, cheek, neck and inguinal area showed no such difference. With regard to the axilla specifically, four studies have been reported, three showing no significant difference in axillary skin surface pH and one indicating that females have an eccrine sweat pH of 7 and males have a sweat pH of 5.6. This paper describes a series of carefully controlled studies aimed at assessing potential gender differences in eccrine sweat and skin surface pH following exposure to a variety of temperature, humidity and time conditions. The results highlight the importance of controlling precisely the time of investigation, site of measurement and, most importantly, the necessity to pre-equilibrate samples in 40 mmHg carbon dioxide (equivalent to arterial CO(2) tension (pCO2)) before determining sweat pH. When these parameters are controlled no gender differences in axillary sweat or skin surface pH are observed. Large differences in eccrine sweat and skin surface pH are found, however, between the vault (hairy region) and fossa (non-hairy region) of the axilla.

Ultrastructure of human eccrine sweat glands with special reference to the transitional portion.

Thin sections of human eccrine sweat glands were observed with the transmission electron microscope. The fine structures of the secretory coil, transitional portion and coiled duct were compared.The secretory coil consists of dark cells, clear cells and myoepithelial cells. Dark cells contain irregularly shaped secretory granules which appear dark after glutaraldehydeosmium double fixation. If osmium is applied first to the specimen, the electron density of the secretory granules is lowered, and they often become vacuoles. These granules originate as an accumulation of secretory substance in the innermost cisterna of the Golgi stack which may correspond to the GERL. This secretory substance contains mucopolysaccharides as it stains intensely with methenamine-silver. Exocytosis of the granules was demonstrated. Clear cells abut the intercellular canaliculi but contain no secretory granules. Well developed smooth ER is spread over the entire cytoplasm, except for the very surface of the cell. The Golgi apparatus is situated near the smooth ER, and sometimes the elements of the Golgi apparatus and smooth ER are intermingled. Glycogen particles are heavily loaded in the cytoplasm of clear cells.The transitional portion, which has not been examined precisely, contains epithelial cells which form a simple cuboidal epithelium and resembles the clear cells of the secretory coil. These cells contain a triangular mass of filaments attached to the zona adherens which are forerunners of the terminal web (periluminal filamentous zone) of the coiled duct. The intercellular interdigitation is weak and basal infoldings are absent in the transitional portion. This portion is provided with myoepithelial cells, which are numerous at the proximal end but sparse in the distal half.The coiled duct consists of two layers of epithelial cells, i. e., luminal and peripheral cells, but the myoepithelium is absent. Numerous mitochondria are heaped in both cells reflecting active reabsorption of sodium ion in the coiled duct.In conclusion, the transitional portion contains structures intermediate between the secretory coil and the coiled duct, and its function may be neither secretion nor absorption; the well developed myoepithelium at the initial segment of this portion may act as a sphincter of the duct system regulating the flow of sweat in the gland.

Some histochemical observations on the human eccrine sweat glands. II. The pathogenesis of miliaria.

Introduction Miliaria is a generic term for those diseases which occur when the free flow of eccrine sweat to the surface is impeded, with the result that sweat is retained within the skin. The sweat-retention dermatoses arise in apparently normal skin or as a complication of any inflammatory disease of the skin. Miliaria is commonest in the summer months, but it can occur in any season if the activity or state of health of the person induces sweating. There is also a definite individual susceptibility to the sweat-retention diseases since not all persons will develop miliaria despite an environment conducive to its development. 1 Usually several days to weeks of profuse sweating must occur prior to the onset of clinical disease. Once established, miliaria may continue indefinitely, provided the stimulus for profuse sweating persists. In the tropics, after recurrent episodes of miliaria rubra, miliaria profunda with its severe